Tikkanen, E, Haverinen, J, Egginton, S orcid.org/0000-0002-3084-9692 et al. (2 more authors) (2017) Effects of prolonged anoxia on electrical activity of the heart in Crucian carp (Carassius carassius). Journal of Experimental Biology, 220 (3). pp. 445-454. ISSN 0022-0949
Abstract
The effects of sustained anoxia on cardiac electrical excitability were examined in the anoxia-tolerant Crucian carp (Carassius carassius). The electrocardiogram (ECG) and expression of excitation-contraction coupling genes were studied in fish acclimatised to normoxia in summer (+18°C) or winter (+2°C), and in winter fish after 1, 3 and 6 weeks of anoxia. Anoxia induced a sustained bradycardia from a heart rate of 10.3±0.77 to 4.1±0.29 bpm (P<0.05) after 5 weeks, and heart rate slowly recovered to control levels when oxygen was restored. Heart rate variability greatly increased under anoxia, and completely recovered under re-oxygenation. The RT interval increased from 2.8±0.34 s in normoxia to 5.8±0.44 s under anoxia (P<0.05), which reflects a doubling of the ventricular action potential (AP) duration. Acclimatisation to winter induced extensive changes in gene expression relative to summer-acclimatised fish, including depression in those coding for the sarcoplasmic reticulum calcium pump (Serca2-q2) and ATP-sensitive K(+) channels (Kir6.2) (P<0.05). Genes of delayed rectifier K(+) (kcnh6) and Ca(2+) channels (cacna1c) were up-regulated in winter fish (P<0.05). In contrast, the additional challenge of anoxia caused only minor changes in gene expression, e.g. depressed expression of Kir2.2b K(+) channel gene (kcnj12b), whereas expression of Ca(2+) (cacna1a, -c and -g) and Na(+) channel genes (scn4a and scn5a) were not affected. These data suggest that low temperature pre-conditions the Crucian carp heart for winter anoxia, whereas sustained anoxic bradycardia and prolongation of AP duration are directly induced by oxygen shortage without major changes in gene expression.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017. Published by The Company of Biologists Ltd. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | anoxia tolerance, bradycardia, fish heart, electrical excitability, excitationcontraction coupling, seasonal acclimatisation |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Biomedical Sciences (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 18 Jan 2017 10:49 |
Last Modified: | 21 Nov 2017 01:38 |
Published Version: | https://doi.org/10.1242/jeb.145177 |
Status: | Published |
Publisher: | Company of Biologists |
Identification Number: | 10.1242/jeb.145177 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:110701 |